The Role of Plasmon Initiated Electron Transfer in Enhanced Raman Spectroscopy

在化学系化学测量和成像（CMI）项目的支持下，扎卡里·舒尔茨（Zachary Schultz）和他在俄亥俄州州立大学的团队正在研究使用激光检测和量化微量蛋白质和其他生物分子的新方法。检测真实世界样品中特定生物分子的能力对于识别病原体、跟踪环境污染物和监测疾病非常重要。被称为表面增强拉曼散射（Sers）和尖端增强拉曼散射（TERS）的专门技术使用纳米颗粒来增加在一些基于激光的测量中观察到的信号的强度。目前，在环境条件下和复杂系统中使用这些技术容易检测到的分子数量有限。为了解决这一限制，由Schultz博士领导的研究小组正在努力更好地了解当蛋白质与纳米颗粒接触时，通过使用激光通过显微镜照射单个蛋白质或蛋白质片段来增加信号的机制。该研究的目标是实现更灵敏的测量，从而能够检测和识别更广泛的生物分子。该项目还通过将研究项目的各个方面纳入每年在俄亥俄州州立大学参加普通化学课程的约8，000名学生的教材中，解决了对技术熟练和科学知情的劳动力的需求。该项目还为本科生和研究生提供了宝贵的研究经验，并支持舒尔茨实验室与智利学生和教师的合作，拓宽了学生对科学的国际性质和影响的看法。 由Zachary Schultz博士领导的研究小组正在测试他们的假设，即与纳米颗粒上激发的等离子体共振相互作用形成的稳定自由基可以瞬时和选择性地增加Sers和TERS测量中生物分子的拉曼截面。该团队的实验测量表明，这种相互作用发生了，甚至改变了观察到的氨基酸色氨酸和一些含色氨酸的蛋白质的Sers光谱。对样品的Sers发射进行成像并应用超分辨率算法，应该可以让研究人员定位和识别与纳米颗粒接触的单个分子。这些测量有望同时解析单个分子的Sers光谱，即使是在复杂的样品中。研究小组从这些复杂的测量中获得的信息应该使他们能够识别出表现出更高灵敏度的蛋白质和其他生物分子，并使他们能够更好地理解是什么使这种增强成为可能。基于对Sers和TERS增强机制的更深入理解，该研究成果可以帮助指导新型和改进型化学传感器的开发，这些传感器对于非常广泛的应用非常重要。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry, Zachary Schultz and his group at Ohio State University are investigating new ways to detect and quantify trace proteins and other biomolecules using lasers. The ability to detect specific biomolecules in real-world samples is important for identifying pathogens, tracking environmental pollutants, and monitoring disease. Specialized techniques called surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS) use nanoparticles to increase the strength of the signals observed in some laser-based measurements. Currently, there are only a limited number of molecules that are readily detected using these techniques under ambient conditions and in complex systems. In order to address this limitation, the research team led by Dr. Schultz is working to better understand the mechanism that is responsible for the increased signals when proteins are in contact with nanoparticles by using a laser to illuminate individual proteins or protein fragments through a microscope. The goal of the research is to enable more sensitive measurements that will make it possible to detect and identify a much wider range of biomolecules. The project also addresses the need for a technically skilled and scientifically informed workforce by incorporating aspects of the research project into educational materials for the approximately 8,000 students who take general chemistry courses each year at Ohio State University. The project also provides valuable research experience for undergraduate and graduate students, and supports the Schultz laboratory’s collaboration with students and faculty in Chile, broadening student perspectives on the international nature and impact of science. The research team led by Dr. Zachary Schultz is testing their hypothesis that stable radicals formed from interactions with excited plasmon resonances on nanoparticles can transiently and selectively increase the Raman cross-sections of biomolecules in SERS and TERS measurements. The team’s experimental measurements suggest that such interactions occur, and even alter the observed SERS spectra of the amino acid tryptophan and some tryptophan-containing proteins. Imaging the SERS emission from a sample and applying super-resolution algorithms should allow the researchers to locate and identify individual molecules that are in contact with a nanoparticle. These measurements are expected to simultaneously resolve the SERS spectrum of the individual molecule, even in complex samples. The information the team obtains from these sophisticated measurements should enable them to identify proteins and other biomolecules that exhibit increased sensitivity, and also enable them to better understand what makes such enhancements possible. Based on the improved understanding of the mechanism for SERS and TERS enhancements, the outcomes of this research can help guide the development of new and improved chemical sensors that are important for a very wide range of applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.